


Lovesick fool

by Issa_Saiko



Category: Shingeki no Kyojin | Attack on Titan
Genre: Bottom Armin Arlert, Cadet years, Consensual Sex, M/M, Plot What Plot/Porn Without Plot, Porn with Feelings, Secret Relationship, Top Jean Kirstein, Underage Sex, Ymir ships it, actually a tiny bit of plot
Language: English
Status: Completed
Published: 2020-08-07
Updated: 2020-08-07
Packaged: 2021-03-05 22:20:36
Rating: Explicit
Warnings: Underage
Chapters: 1
Words: 4,465
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25772725
Author URL: https://archiveofourown.org/users/Issa_Saiko/pseuds/Issa_Saiko
Summary: Story in which Jean is a horn dog and can’t keep his hands off a certain blonde for too long despite the peering eyes all around them.
Relationships: Armin Arlert & Jean Kirstein, Armin Arlert/Jean Kirstein
Comments: 10
Kudos: 199





	Lovesick fool

**Author's Note:**

> So I wrote this story and then realized while editing that they were like 15 during their cadet years? So I’m tagging it as underage. It gets kinda confusing when you see characters like Reiner that look in their 20s. Anyway, hopefully you enjoy it!

Jean Kirschtein was a cadet; a soldier in training. One that was expected to be well behaved and respectful, but Jean was also human, and like every human, he had needs. Very specific _needs_. It’s been weeks since his last lay, and he was slightly annoyed. If he had it his way, it wouldn’t have taken this long, but there were always peering eyes, and there never seemed to be a good enough time to do anything with his love.

This lover in question was a boy named Armin Arlert, one of his fellow cadets. Armin was a small, androgynous boy with blonde hair and oh so bright blue eyes. He was the embodiment of an angel, and the image of Jean’s fantasy. 

It was breakfast in the barracks and Jean watched the boy from afar as he ate. Was it pathetic that even just watching Armin eat was turning him on? He watched as Armin wrapped his pretty pink lips around a piece of bread, Jean couldn’t help but imagine it was his dick, until Armin bit down. Jean cringed. God, what the hell was wrong with him? Why was he so horny? Jean sighed. 

His buddy Marco must have noticed his mood. He turned toward him. “What’s wrong Jean? You’ve barely touched your food.” The voice sounded concerned. Poor Marco was just being a good guy, but Jean couldn’t exactly tell him the real reason he was in a bad mood. “I’m just tired,” he lies, “I didn’t get much sleep last night.” 

Connie joins in then, “Well you should've got more sleep dude. We’ve got sparing practice today.” he says between a mouth full of porridge. 

Jean groans. It looks like it’s gonna be another busy day. He casts a glance back in Armin’s direction, just to meet the boy's eyes. Armin gives him a small smile. It looks almost apologetic. Does he know how much Jean needs him right now? 

Jean wanted nothing more than to go over to the boy, bend him over the table, and— 

“Jean!” A voice snaps him out of his thoughts. He turns to see Connie looking rather annoyed. “Jeez dude, you really are out of it. I’ve been calling your name!” 

Jean sheepishly rubs the back of his neck, “O-oh right, sorry…” He hoped Connie didn’t notice him staring at a certain blonde. Armin and him were trying to be as discreet as possible, not knowing how their friends or the higher ups would take to their relationship. That’s also the reason why Jean is still sitting over here and not next to Armin; so they don’t cause suspicion. It was painful for the both of them, but they knew what could be at stake. 

‘It’s fine,’ Jean thought to himself, ‘you’ll be able to see him soon enough. Just calm down.’ 

“Well anyway! I was talking about the sparring practice. Shadis is assigning partners this time. He put me against Annie! I’m totally gonna die dude!” Connie shook with fear. 

Wait what? Connie has Jean’s full attention now, “Partners? How do you know who you’re assigned too?” 

“Haven’t you heard Jean? They’re posted outside along the corridor,” Marco Informed. “Though I haven’t gotten the chance to check it out yet. I guess we can both go look at it now if you’re finished eating.”

Jean nodded, “Yeah, yeah I’m finished. Let’s go.” 

* * *

There on the postboard were the names of everyone. Apparently the name across from yours would be your partner. Jean gazed along the board with Marco. 

**_Marco Bott_ ** **—** **_Thomas Wagner_ **

“Oh neat! I’m with Thomas,” Marco looks relieved. He turns over to Jean. “Who did you get?”

**_Jean Kirschtein — Armin Arlert_ **

Jean was at a loss for words. He didn’t know whether to be excited or not. This meant more time with Armin, but Jean knew he won’t be able to help himself around his cute boyfriend, especially after not seeing him properly for over a week. 

Marco must have seen the name beside his. He smiled. “Oh you’re with Armin. That’s cool, he’s really nice.” 

Jean scoffed, feigning indifference. “Yeah, whatever. This’ll be a piece of cake.” 

Marco frowned. “Hey, go easy on him Jean. Fighting isn’t really one of his strong suits.” 

Jean waved his hand dismissively. “Yeah, yeah I’ll be gentle… I always am.” 

“What was that?” 

“Ah nothing. Forget it.” 

* * *

Soon enough, every cadet was reporting to the training grounds for their sparring matches. Chief Instructor Shadis was there to give a brief overview of the task. Jean drowned him out, they’ve done this at least 3 times already, everyone already knew what to do. Jean chose to direct his attention to the blonde next to him instead. Armin looked to be paying close attention to what Shadis had to say. He was pulling his concentrated look, the one where he had his fist against his lips. Jean thought he was adorable. He nudged Armin to get his attention. Armin immediately looked up, a little embarrassed to be caught in his daze. 

“I was surprised to see you were my partner, Jean… but more so I was relieved.” Armin was giving him one of the warmest smiles he’s ever seen. Jean’s heart skipped a beat, but he tried to keep it cool. 

“Relieved, eh?”

“Well yes… I know you wouldn’t hurt me if you could help it, and I… I haven’t seen you around in awhile, huh? When was the last time we were alone—”

“In that abandoned church during the last training expedition.” Jean smiled to himself at the memory. They managed to get away for a little while during a stop. Jean remembered it like it was yesterday. “You were screaming my name in the pews.” 

Armin went beat read, “I-I wasn’t! Don’t admit to such a thing s-so loud, Jean…” 

Jean chuckled, but it soon died out, a thoughtful look appearing on his face instead, “You know… It’s been way too long, Ar’,” Jean puts a hand on his shoulder and looks down into his eyes, “I… I’ve _missed_ you.” 

The meaning of his words wasn’t lost on Armin. He knew what Jean craved, and to be honest, Armin was craving the other man’s touch as well, but they couldn’t do anything right _now._ They were soldiers and they were expected to act as them. 

Just as Armin was about to say so, Instructor Shadis spoke up, “No questions? Then we shall commence the training starting now! Get into position with your partner and when I say start, you will attack!”

As he gets into position, Jean brushes against Armin on the way, whispering. “Don’t expect me to be easy on you now.” God only knows how much Jean wants to jump the boy. 

Armin quivers a little. They stand facing each other, 12 feet apart as instructed. Jean gives Armin a dangerous look, one that makes him feel like he’s prey being ogled at by a beast. Armin doesn’t know if he should be scared or not. He knows Jean would never hurt him but that’s not what he’s worried about. It’s that _look_ Jean is giving, it’s the coy smile he always sees before Jean plans to do something lewd with him. But Jean wouldn’t try to do something like _that_ here of all places, right?

Armin frantically waves his hands in front of him. “Jean, you aren’t going to do something stupid, are y—

“Start!” The loud shout of Shadis’ voice cuts Armin off mid sentence and before he can even blink, Jean is on top of him.

“J-Jean—” Armin’s cut off as Jean tackles him into the dirt. Armin tries to push him off but Jean grabs his wrists and places them above his head. Armin then tries to kick him but Jean was ahead of that too. With one hand still holding onto Armin’s wrists, Jean uses the other to grab one of Armin’s offending legs. He holds the leg in the air and takes the opening to settle between them. Armin definitely has a harder time kicking now. Jean looks down at him and smirks and only then does Armin realize what a compromising position they’re in. 

He blushes and wiggles harder, pushing against Jean's hold, “W-what do you think you’re doing?”

“The task was to restrain your enemy, right? Well that’s what I’m doing, oh and stop wiggling around, you’re gonna make this awkward.” Jean teases. 

Armin huffs, “It’s already awkward! This position is—it’s embarrassing!” Armin looks around exasperated, thankfully it looks like everyone is busy with their own fights to pay them any mind. Armin glances past a screaming Connie, running away from Annie in the distance.

B-but even so! Armin won’t forgive Jean for this. Who does he think he is? 

“Aw, but you look so cute when you’re embarrassed~” Jean coos, “Look, if you want me to get off just say, ‘I give.’” 

Armin scowls, he wasn’t gonna give up so easily, especially not when Jean was being all cocky about it. Armin angrily tries to break free again. It was futile but the action suddenly gave him an idea. If Jean was gonna embarrass him then Armin would get payback too. 

Armin continues struggling, but this time, he arches his back against Jean's hold so that he’s flush against him. Then he purposefully grinds down against his crotch. Jean groans and glares at the boy, but Armin just looks up at him innocently. 

“Ar,’ what do you think you’re doing?”

“Ah, I’m just—mmh—trying to break free, Jean.” Armin lays on his sex voice thick and moans every chance he can get. 

“Hey… stop that.” Jean was shocked. Usually Armin was so bashful and shy. To think he was capable of doing _this_ in public was mind-boggling. 

“Stop what? Ah, Jean, you-you’re so strong… and so-so much bigger than I am~ How am I s-suppose to fight against you?” Armin grinds up again and this time Jean almost growls. He could feel his cock stir in his pants. Armin’s voice was always his weakness and the little minx knew that. 

“Dude, I’m serious, everyone will find out about us if you keep doing that.”

“Then all you have to say is, ‘I give,’ remember?” Now Armin is the one with the cocky smirk.

Jean was never one to claim defeat so easy. He scoffs, “I’ve got a better idea.” 

Jean lets go of Armin’s wrists and grips at his waist. In the flash of a second, he has Armin on his stomach with his wrists pinned to his back. Armin gasps. 

“You're being a bad boy, Armin.” Jean whispers in his ear, “You'd risk everything just to be a tease. God, do you even know how much I’m holding back right now?” Jean grazes his hand over Armin’s neck, “I swear I’m gonna ravage you after this, I don’t care if I have to steal you away for it. I _need_ you.”

Armin whimpers beneath him, “I-I need you too. Just as much, Jean.” Truth be told, Jean being so rough was doing something to Armin. He never thought of himself as the kinky type, but right at this moment he wanted Jean. The whole training exercise was completely gone from his mind. 

“J-Jean?”

“Yes, love?”

“I give… so can you turn me over now?”

Jean fumbles for a moment, “O-of course!” He flips Armin over and helps him sit up, “Was—um…. was I too rough?” Jean worries for a moment. He was so caught up in the situation he didn’t even think about it. 

“A little, but it’s fine. Actually… it was more than fine…” Armin blushes brightly. The sight alone has Jean twitching in his pants. It’s then that he realizes just how hard he actually is. Armin seems to be having a little problem too. 

Thankfully, the fabric of their garters shielded the sight a bit, but it was still prominent. Jean cleared his throat and repositioned his sitting to cover his crotch. Armin did the same, crossing his legs. They laughed a bit to try to alleviate some of the sexual tension. 

Although, unknowing to them, Ymir, who was sitting on top of Sasha, saw the whole thing.

“Nice.” Was all that she said as Saha garbled in the dirt. 

Shortly after, Shadis ordered everyone to stop, seeing that most of the cadets' partners either surrendered or were restrained already. 

Jean helped Armin off the ground and by that point, their, erm, “excitement” had calmed down. Both boys exchanged sly smiles as Shadis explained directions for the next match. Armin leaned over to whisper in Jean’s ear, “After the showers, meet me in the storage room on the right wing before dinner.” Armin then looked both ways before sneaking Jean a quick kiss on the cheek. Jean watched with heart eyes as his love walked away and got into position again. He couldn’t wait for the evening's plans. 

* * *

Jean practically ran out of the showers after getting changed into his normal clothes. Connie wanted to talk to him (more like whine about his bruises) but Jean was having none of it. He was determined to meet Armin. He left with no excuse, merely brushing Connie off before exiting. 

Once Jean arrived in the, practically abandoned, storage closet he realized he may have been a little too eager to get there. There was no way to tell if Armin was on his way yet as Jean purposely washed on the opposite shower wall. To avoid distraction, really, it was something they both agreed on. Better safe than sorry, but Jean was having a dilemma. Was Armin coming? Maybe something came up, or he couldn’t get away from his two close friends that were always attached to his hip. Jean groaned. 

Just when he thought he couldn’t wait another minute, Jean heard quiet footsteps outside the door. He watched as a dainty hand and blue eyes peaked inside, unsure. They lit up a second later, as Armin, beautiful, beautiful, sweet Armin stepped the rest of the way inside and gave Jean a bright smile. 

“Sorry I took so long, I couldn’t get away.” Armin rolled his eyes. 

Jean laughed, “It’s ok. I thought that might be it.” 

Armin blushes brightly then. “So uh, now that we’re here. Are we, uh—you know…” 

Jean smirks as he pulls Armin closer to him by the waist. “Did anyone see you come in?” Jean whispers in his ear. 

Armin relaxes instantly in his hold, “N-no, no one was out there…” 

“Good.” Jean breaths in Armin’s scent. His hair was still a little damp from the shower and it smelled insanely good. Jean brushed some of the stray locks behind Armin’s ear and kissed down along his cheek to his neck before coming back up to his lips. Armin hummed into the kiss and wrapped his arms around Jean’s neck. 

They kissed, slowly getting more and more passionate by the second. Jean ran his hands all over his boyfriend while adding his tongue to the kiss which Amrin happily accepted, threading his fingers through Jean’s hair and pulling lightly. 

Armin, surprising, was the first to pull away. “Ah, Jean… please.” In an act of pure boldness, Armin tugs on Jean’s belt and looks at him with begging eyes. Jean gulps. Before he can say anything, Armin gets on his knees in front of him and starts to unbuckle his belt. All while looking at Jean smugly.

Jean was in shock. He was overcome with so much affection and lust in that instant. When Armin reached into his boxers, Jean was already half hard. “Hey, you know you don’t have to—“ 

Jean was cut off as Armin licked across the head of his dick. He cursed. Armin was never this forward. He sucked on the tip and moaned. Jean could’ve sworn his soul left his body. He took the liberty of leaning against one of the metal shelves in the closet, and after Armin performed a particularly strong suck, Jean gripped one of the bars for life. “F-fuck.”

He could feel Armin smirk against him, and then he was taking him farther into his mouth. Jean groaned as he felt Armin practically deep throating him at this point. When did he get so good at that? 

Oh no, he was definitely gonna cum if Armin kept it up. He tugged on Armin’s hair lightly. “Ok, t-that’s enough.”

Armin withdrew with a lewd pop, smirking up at Jean devilishly. He knew how much he was affecting him, didn’t he? Well now the tables were about to turn. 

Jean yanks Armin up by the wrists. Armin smiles up at him and leans in for a kiss but Jean quickly turns him around and pushes him against the shelf. 

Armin lets out a shocked moan and Jean suddenly remembers earlier on the training grounds Armin mentioning liking it rough. It pleased Jean to know his angel was a bit on the kinky side. 

He leaned over to whisper in his ear. “You wanted to tease me, huh?” Jean heard an audible gasp coming from the boy. He tilted his head to see Armin biting his lip with a flushed face. Jean chuckled and started nipping along the length of his neck. Now he was embarrassed? After everything they’ve done together, it was kinda heartwarming that the boy was still shy about their endeavors. It was also a bigger turn on for Jean than he’d like to admit. Seeing the boy so timid like this did something to him he couldn’t explain. It made him want to bend Armin over right now and just take him like this. 

Despite Armin’s shyness he seems to have gained some newfound confidence, pushing his hips back against Jean’s crotch, which was beginning to swell. “Yes, Jean~ I-I wanted to excite you.” God, did he know what he did to him? How much his small, breathy voice lured him in. 

“Oh I’m excited alright,” Jean took his right hand and smacked Armin’s ass. The action had Armin arching his back. He moaned, now gripping the sides of the metal shelf for dear life. Jean chuckled and groped the cheek possessively, “so take responsibility,” he muttered into Armin’s ear. 

Jean could have sworn the boy subconsciously spread his legs a little at the words. So he really did like it rough? What a slut he was, Jean thought. But he was _his_ slut. 

Jean chuckled lightly before taking a step back. He began removing the rest of his clothes while ushering for Armin to do the same. Armin unbuttoned his shirt with shaky fingers and pulled it off. As soon as he reached for the buckle of his pants, Jean took over, sneaking a hand around and pulling them down in a slow, teasing manner, along with his boxers. Armin blushed hard when he felt Jean grope him _there_. 

“So tiny, yet so excited you are.” Jean laughed. He knew Armin secretly liked being emasculated. “You gonna come already?” Jean whispered in his ear as he squeezed him tighter. Armin cried out, throwing his head back against Jean and moaning despite the slight pain. 

“J-Jean! Please…” Armin was begging at this point, “I-if you don’t—ha—h-hurry up, s-someone will come to look for u-us.” 

How clever his boy was, Jean wasn’t gonna give in so easily though. “Let them see us then. Let them see you bent over, completely at my mercy. I wonder what they’d say? I’d love to see their reaction. Anyone would be blessed to witness you in this position.” 

Armin moaned loudly at his words. It’s not like he _wanted_ to be seen but Jean’s voice was a complete turn on, the man was insanely good at dirty talking. Something Armin always fell victim to when they were intimate. 

Despite wanting to tease his beloved more, Jean knew Armin was right so he reached into the pocket of his discarded pants and pulled out the vial of lube he brought. 

Armin got back into his previous position and braced himself for the intrusion of Jean’s fingers. He groaned and gripped tightly onto the shelf when it finally came. Jean shushed him quietly and whispered sweet nothings into his ear as he prepped him. The slight stinging pain soon turned into blissful aches. It was intoxicating. Armin was unaware of himself pushing back against the fingers until he heard Jean chuckle behind him. 

“I take it you’re ready, love?” Jean questioned, still pushing his fingers inside him. 

Armin didn’t trust his voice so he settled for humming in affirmation. “Mmh~”

Jean threaded his fingers through Armin’s hair with his other hand and tugged lightly. “I’m sorry, what was that? You’re going to have to use your words, darling.”

Jean really just couldn’t keep from teasing him. It was so embarrassing. 

Armin huffed. “P-please, Jean. I can’t take it anymore!”

Jean smiled. “Just tell me what you want, baby.”

“I want you in-inside me—I want you to fuck me~” 

Jean laughed and patted his head like a dog. “Your wish is my command.” 

Jean retracted his fingers, and just like that, Armin felt empty. Jean used the extra lube to slick up his cock. He grabbed Armin’s hips and settled behind him. 

“You ok, Ar’?” Jean wanted to be sure. 

It was endearing, really, but Armin was far past ready. He _needed_ him now. “Yes, Jean please…” Armin whispered. He was practically shaking with want. 

Jean smiled. He kissed the back of his head before slowly pushing inside. 

Armin’s head lolled back as Jean entered him. He let out a pleased moan “S-so good.” He murmured. 

Jean himself let out a long drawn out groan at the feeling of the tight heat around him. He leaned down to kiss along the side of Armin’s neck. “Does it hurt?”

“No, goddesses no. It f-feels wonderful. You can go h-harder.” 

Jean wordlessly complied. He set up a fast pace that had Armin moaning with practically every thrust. The shelf was shaking loudly from the force at this point. Would someone hear? Jean didn’t care. He went harder, searching for that spot that had Armin seeing stars, and when he found it, Armin outright mewled.

“Ah—Je~an!” 

_Bingo,_ Jean thought with a smirk. He started thrusting there vigorously. 

Armin was moaning so loud he had to put a shaky hand over his mouth to try to muffle it. Jean lifted his hand and put it against the bar instead. “For just this once…. don’t keep your beautiful voice in.” Jean threaded his fingers atop of Armin’s along the metal bar. “Hold on tight, darling.” He whispered. 

Armin wanted to cry. Not only because of the great sex, but because he just loved this man _so_ _much_. He wanted to tell him so, but he was too far gone for words at this point. All he could do was scream and moan in pleasure. He was so close already it was embarrassing. All it took was one more calculated thrust from Jean and Armin was spilling over himself with a high pitched whine. 

Jean felt Armin shake and tighten around him. “Did you cum from just me fucking you? Ah, shit—that’s _so_ hot.” Jean groaned. He slowed his thrusts. “Fuck—I’m so close, can I do it inside?”

It took Armin a moment to even register the question. His whole body suddenly felt weak. He collapsed onto the empty shelf beneath him and absently nodded his head to Jean’s request. Armin almost regretted his decision when he felt Jean continue at a rough pace. He could only moan weakly at the over stimulation, accepting the push and pull of being used thoroughly.

Soon Jean was coming too, grabbing onto Armin like his only lifeline. It took a minute of them panting heavily before Jean decided to pull out. 

Armin felt his legs shake underneath him and as he sat up, his knees buckled. Jean quickly reached out to keep him up. Armin blushed at the act. “Shit, are you ok?!” 

“Ah, I just feel a little weak. My legs were shaking…”

Jean scoffs in amusement. “ _That_ good, huh?” 

Armin nudges him playfully. “S-shut up.” He didn’t want to inflate Jean’s ego more than was necessary. 

Jean just laughs. There’s a long pause where they just held each other in silence, enjoying the other's company. Jean was the first to speak up. “We should probably head back now, huh?” 

Armin sighs. He wanted to say no but the logical part of him knew they had to. “I suppose you’re right…”

Jean must’ve noticed the forlorn expression on Armin’s face. He reaches out to pinch his cheeks. “You’re so cute.” 

Armin blushes. “Wha—I am not cute!”

“Yes, you are. And I love you so fucking much, Ar.” 

Armin’s mouth falls open in shock. He wasn’t expecting a confession. “I-I love you too, Jean.” 

“Maybe one day… we won’t have to hide.”

* * *

Jean steals a look at Armin, watching as he makes his way into the cafeteria. They both decided it would be best if they showed up at different times. It’s only been a few minutes and Jean already misses him. 

Just then, Connie comes to sit next to him with a tray of food. “Jean! Dude, where did you go earlier? You left before I could tell you how I got this huge ass bruise!” Connie points to a dark bruise on his elbow. 

Jean rubs the back of his neck. “Oh, uh I had to check something I left in the dorms.” Stupid answer, Jean thought. Thankfully, Connie was a stupid person and didn’t question it further. Bless his heart. 

“Oh. Well Annie did this crazy move that spun me around like this and then—” 

Jean again blocked out what Connie was saying for the second time that day. He was too busy thinking about a certain blonde. 

Marco rolls his eyes at Connie’s overreacting and turns his attention to Jean. “How did your training go, Jean? You didn’t hurt Armin, did you?” 

“It was great…” Jean replies monotonously, still in his daze. 

Marco quirks his eyebrow at his tone. He follows Jean’s sights in confusion before finding them trained onto the boy in question. 

From across the room, Armin seemed to laugh at something funny Eren and Mikasa said. Marco turned back only to notice Jean now smiling a little at the sight. Armin must have felt the staring because he soon met Jean’s gaze. 

Marco watched as Jean gave him a subtle wink. Armin blushed and looked away after that. 

Huh…That’s weird. Then it hit him. Marco studied Jean. He knew that look. 

It was the look of a lovesick fool. 

Oh. _Oh_. 

Well wasn’t that something? 

**Author's Note:**

> Comment below what you think or if you have any ideas for a continuation. Who knows I might expand on this. Also let me know if you have any critiques or see any errors. I know I have a tendency to add too many details to the point where I over explain things, but I hope that’s not the case here!


End file.
